Conventionally, for example, Patent Literature 1 proposes an optical sensor in which plural photo-diodes are formed on a semiconductor substrate. On the formation surface, a translucent layer having translucent property is formed. On the translucent layer, a light shielding mask having light shielding effect is formed. On the light shielding mask, plural light propagation areas are formed. In the optical sensor, an area of light incident upon a light receiving surface of the photo-diode is specified by the light propagation area of the light shielding mask.